Expendable unitary quick mount abrasive discs and support pad therefor

ABSTRACT

The combination of an abrasive finishing device and a support member therefor. The support member includes a body having a threaded central opening with a flange at one end thereof. A fastening member having a threaded shaft and flange is permanently affixed to the abrasive finishing article by a resiliently deformable retainer press fitted over the threads on the shaft in such a manner that the flange on the fastening member is disposed entirely below the working surface of the abrasive finishing device. The retainer is a washer shaped member having an inner diameter which is less than the outer diameter of the threaded shaft on the fastening member and grips the thread on the shaft.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority of U.S. Provisional Patent Application No. 61/003,102 filed on Nov. 13, 2007, and the disclosure thereof is incorporated herein by reference and is a continuation in part of U.S. application Ser. No. 11/908,491 filed Sep. 12, 2007.

FIELD OF THE INVENTION

This invention relates generally to abrasive finishing articles and, more particularly, to the combination of an abrasive disc support pad and a disposable abrasive finishing disc in which the securing member affixed to the disposable abrasive finishing disc is entirely below the working surface of abrasive finishing particles contained on the abrasive disc.

BACKGROUND OF THE INVENTION

In the use of rotatably driven abrasive finishing articles and particularly coated abrasive finishing articles and non-woven fibrous abrasive material, such abrasive finishing articles are adapted for use on a wide range of air and electric powered tools. Traditionally, such an abrasive or non-woven material finishing article are discs removably attached by way of a support pad assembly to a power tool. When the support pad assembly is rotated, the disc rotates with it permitting the moving abrasive disc surface to effectively finish the surface of a work piece. A variety of hub structures have been used in the prior art to secure the abrasive finishing discs to the power tool.

The earliest and very common of such structures includes a support pad having a reinforced central aperture arranged to be engaged over the threaded end of a rotary shaft of the power tool. The abrasive finishing disc is placed on the flat surface of the pad and a flanged nut is turned down onto the threaded end of the rotary shaft protruding through the disc. When the nut is tightened, the flange lays flush against the abrasive surface of the disc and clamps the disc to the support pad.

This traditional mode of attaching the abrasive finishing disc to the rotary power tool has two major disadvantages. The first of these is that by engagement of the rotating finishing disc against the work piece a large amount of torque is imported to the hub which tends to tighten the nut onto the threaded shaft of the power tool making it quite difficult to remove the nut in order to replace the disc after it is spent and usually involves the use of tools. In many heavy industrial applications, such abrasive discs have to be replaced quite often. As a result, when considering the number of power tools which may be in use at any given time, there is an excessive amount of downtime necessitated by such disc replacement. A second disadvantage is that the flange of the nut extends above the surface of the abrasive material on the finishing disc and the workers using the disc must be quite careful to prevent the flange on the nut from engaging the work piece which, in most cases, would impart damage to the work piece. Such severely limits the surface area of the abrasive finishing material on the abrasive finishing disc which may be used in finishing the work piece.

To overcome these problems, abrasive finishing discs were developed wherein a fastener was adhesively secured to the back surface of the abrasive finishing disc. One such fastener included a raised boss having a central aperture whose rim is turned inward and shaped to form a screw thread (referred to as a type R fastener) which receives the threaded end on a molded rubber support pad. Another such fastener is a threaded stud which is received by a female thread disposed in a molded rubber support pad (referred to as a type S fastener). These structures have allowed the user to attach and remove the abrasive disc to the support pad rather quickly. The necessity of utilizing adhesive materials to secure the fastener to the abrasive finishing disc obviously increased the manufacturing costs both as a result of the increased amount of material and labor.

In view of the foregoing disadvantages of the prior art, it is desirable to provide a support member and a disposable abrasive finishing disc which includes a structure such that the device for attaching the disc to the support pad is entirely below the surface of the abrasive material. The support member must also include structure for receiving the attaching apparatus secured to the abrasive disc. It is also desirable that the disc and the fastening member secured thereto be formed in such a manner that the disc can be disposed of when the abrasive material has been used. It is also desirable that the abrasive finishing disc may be quickly and easily removed and a new disc attached without the necessity of utilizing tools and without the attachment of any external adapters or other devices to accomplish that purpose.

SUMMARY OF THE INVENTION

An abrasive finishing disc for use with a support member wherein the abrasive disc includes a circular disc having first and second surfaces with abrasive finishing material on at least the first surface, a fastener member including a threaded shaft having a flange extending radially outwardly from one end thereof extending through an opening centrally disposed in the circular disc with the flange engaging the first surface of the disc and the threaded shaft extending beyond the second surface of the disc and a resiliently deformable retainer member press fitted over the threaded shaft, gripping the threads on the shaft and engaging the second surface of the disc with sufficient force to permanently secure the disc between the flange and the retainer member and to cause the flange to be entirely disposed below the first surface of the disc.

The combination of an abrasive disc support member and a disposable abrasive finishing disc comprising a cylindrical body having an outwardly extending flange engaging the disc and defining a centrally disposed threaded opening therethrough. The opening adjacent the flange defining a cup shaped recess for receiving a central portion of the disc and an abrasive disc comprising a circular disc having first and second surfaces with abrasive finishing material on at least the first surface. A fastener member including a threaded shaft having a flange extending radially outwardly from one end thereof extending through an opening centrally disposed in the circular disc with the flange engaging the first surface of the disc and the threaded shaft extending beyond the second surface of the disc and a resiliently deformable retainer member press fitted over the threaded shaft, gripping the threads on the shaft and engaging the second surface of the disc with sufficient force to permanently secure the disc between the flange and the retainer member and to cause the flange to be entirely disposed below the first surface of the disc.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation in cross-section of the combination of an abrasive disc support pad and a disposable abrasive finishing disc;

FIG. 2 is a perspective view of an abrasive finishing disc constructed in accordance with the principles of the present invention;

FIG. 3 is a perspective view of a support pad of the present invention;

FIG. 4 is an exploded view partially in cross section of an abrasive disc and a fastening member constructed in accordance with the principles of present inventions;

FIG. 5 is a schematic illustration in cross-section showing the abrasive disc and fastening member assembled;

FIG. 6 is a schematic cross section of flat circular plate of the support pad;

FIG. 7 is a schematic cross section showing the plate of FIG. 6 formed to provide a depressed center;

FIG. 8 is a schematic view in cross section of an alternative embodiment of the support pad of the present invention;

FIG. 9 is a perspective view of an alternative fastener;

FIG. 10 is an elevational view of the fastener of FIG. 9;

FIG. 11 is a cross-sectional view of the retainer member;

FIG. 12 is a cross-sectional view illustrating the fastener secured to a non-woven fibrous abrasive finishing disc;

FIG. 13 is a cross-sectional view of a support member for use with the finishing article as illustrated in FIG. 12; and

FIG. 14 is a partial cross-sectional view taken at 14-14 of FIG. 13, illustrating the manner in which the retainer member is affixed to the fastener.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides an abrasive finishing disc having a fastener affixed thereto in such a manner that the abrasive finishing disc forms a depressed center such that the flange which holds the abrasive disc to a support pad is disposed completely below the surface of the abrasive finishing material which forms a part of the abrasive disc thereby maximizing the amount of surface area which is usable. The abrasive discs may be made of coated cloth or fiber or non-woven three dimensional fibrous abrasive material as is taught in U.S. Pat. No. 5,858,140 or such material having a reinforcing scrim as taught in U.S. Pat. No. 3,688,453. The fastener device includes a threaded shaft having male or female threads for attachment to a support pad. The support pad includes a depressed center area which cooperates to receive the depressed portion on the abrasive disc so that when the disc is fastened in place for use on the support pad, the fastener flange remains disposed below the abrasive finishing particle surface. The depressed center for the support pad is created by forming plates preferably formed from molybdenum disulfide filled nylon sheet but may also include other materials such as a lamination of molybdenum disulfide filled nylon and cloth supported neoprene plastic. Through utilization of such materials the plastic plates included as part of the support pad have a depressed center configuration when assembled on the support pad body. The degree of flexibility of the support pad may be determined by the number, thickness, diameter and the relative position of the plates contained in the pad to provide the desired amount of flexibility depending upon the particular application to which the abrasive finishing device is being applied.

By reference to the drawings, and more particularly to FIG. 1, there is illustrated schematically and in cross section an abrasive finishing article and a support pad therefor as constructed in accordance with the principles of the present invention. As is shown in FIG. 1, as abrasive disc 10 formed of non-woven abrasive material 12 has a fastener 14 secured in a centrally disposed opening thereof. As illustrated, the fastener 14 after being inserted into the opening is upset as shown at 16 to clamp the non-woven abrasive material surrounding the opening between the upset portion 16 and a flange 18 to thereby firmly secure the fastener 14 to the non-woven abrasive finishing article 12. The non-woven abrasive finishing article 12 is formed about its central opening so that there is provided a depressed center section 20. The utilization of the depressed center section 20 causes the surface 22 of the fastener 14 to be disposed totally below the surface 24 of the non-woven abrasive finishing article 12. By so positioning the surface 22 it will be clear to those skilled in the art that when the abrasive finishing article 10 is placed in use against the work piece the fastener 14 including the surface 22 does not contact the work piece. The fastener 14 includes a shaft 26 having externally disposed male threads 28 thereon for fastening the abrasive finishing article 10 to the support pad 30. The support pad 30 includes a body 32 having an internally threaded bore 34 which is adapted to receive the threaded shaft 26 of the fastener 14 at one end thereof and to receive a drive member such as an arbor which is in turn, affixed to an air or electric power tool to rotate the finishing article 10 against a work piece. Alternatively, the threaded shaft 26 may be formed with female threads which receive a male threaded member in the support pad. It should also be understood that the bore 34 may be altered to receive discs having the prior art type S fasteners secured thereto. Such renders the support pad of the present invention more versatile and capable of being used with the abrasive disc of the present invention and prior art abrasive discs. The body 32 includes a plate retaining flange 36 extending radially outwardly from one end thereof. Positioned against the flange 36 is a circular plastic plate 38 upon which the non-woven abrasive finishing article 12 rests when the abrasive finishing disc is affixed to the body 32. If desired, a plurality of such plates may be utilized and as illustrated in FIG. 1, there is an additional plate 40 disposed on top of the plate 38. It is of particular importance to note that the plates 38 and 40 are formed about centrally disposed openings thereof in such a manner as to provide a depressed center 42 into which the depressed center section 20 of the abrasive finishing article 10 fits when it is secured to the body 32. Such construction further assures that the surface 22 of the fastener 14 is disposed at all times below the operational surface 24 of the abrasive finishing article 10. The plates 38 and 40 are preferably made of molybdenum disulfide filled nylon sheet material but may be made of other materials including a lamination of molybdenum disulfide filled nylon and cloth support neoprene. In any event, the material which forms the plates 38 and 40 is such that when they are formed to provide the depressed center 42 they retain that shape. After the plates are assembled against the flange 36 a base ring 44 is press fitted over the surface 46 of the body 32 to retain the plates 38 and 40 securely in place against the flange 36. As noted, the base ring 44 is constructed to have an upwardly extending peripheral rim 45 which forms a recess into which the depressed center sections of the plates 38 and 40 fit. The depressed center sections of the plates 38 and 40 may be formed upon assembly of the base ring onto the body or alternatively, may be pre-formed.

The structure of the support pad 30 as illustrated in FIG. 1 is such that the flexibility of the support pad is fixed and is determined by the diameter and thickness of the plates 38 and 40 as well as the number of such plates used. It will be understood by those skilled in the art that if a single relatively thin plate such as that shown at 38 is utilized there will then be provided a maximum degree of flexibility to the support pad. As the plate is increased in thickness or as additional plates are added, the flexibility of the support pad is decreased.

FIG. 2 illustrates in perspective view an abrasive disc 48 which as shown is a surface conditioning disc. As is shown, the fastener 50 is affixed to the abrasive disc and includes threads as described above for affixing the disc to a support pad. A support pad 52 is shown in FIG. 3 and is constructed to provide the depressed center area 54 as above referred to. As is shown in 53, the support pad includes a plastic plate 56 which is secured to the body 58 by the base ring 60 as above described.

FIGS. 4 and 5 illustrate the manner in which one embodiment of the abrasive finishing article is constructed. As is shown, there is provided an abrasive disc 62 having a centrally disposed opening 64 therein. The disc 62 includes a coated abrasive finishing surface 66 thereon. Also illustrated is a fastener 68 which includes a disc retaining flange 70. A reduced diameter portion 72 extends upwardly from the disc retaining flange 70 and provides a surface around which the opening 64 of the disc 62 is positioned. The threaded shaft 74 extends upwardly from the reduced diameter portion 72 and as above described is used to affix the abrasive finishing disc to the support pad.

To form the abrasive finishing article and make it ready for use on a support pad the fastener 68 is inserted through the opening 64 until the flange is seated against the abrasive finishing surface 66. This combination is then inserted into an assembly fixture which is formed to have a cavity therein. The disc 62 is seated on the fixture with the surface 76 around the opening 64 disposed adjacent the cavity. A force is then applied as shown at F against the flange 70 to force the fastener into the cavity and against a member of the assembly fixture which will upset the upper port of the reduced diameter portion 72 as is illustrated at 78 in FIG. 5. That is, the fixture is designed in such a manner that the upper portion of the decreased diameter portion 72 of the fastener is caused to move outwardly and thereby clamp the area around the opening 64 of the disc 62 between the flange 70 and the upset portion 78 thereby securely and permanently affixing the fastener 68 to the disc 62. As is also illustrated in FIG. 5 when the force F is applied the area around the opening 64 of the disc 62 is formed to provide a depressed center 80 to the disc 62.

By reference now more particularly to FIGS. 6 and 7, there is illustrated the manner in which the plates 38 and 40 are formed to provide the depressed center portion thereof. As is illustrated in FIG. 6 a flat plate 80 preferably formed of molybdenum disulfide filled nylon sheet is provided and includes a centrally disposed opening 82 therethrough. The plate 80 is positioned within a fixture and a tool is applied to the surface area surrounding the opening 82 to cause the plastic material forming the plate 80 to become permanently deformed to provide the depressed center 84 as shown in FIG. 7. This deformation causes the plate surrounding the opening to have a curved profile so that a first surface 86 surrounding the opening is concave and a second surface 88 on the opposite side thereof surrounding the opening is convex. As above indicated, any number of such plates may be pre-formed and provided and stacked one upon the other to provide the desired flexibility. As is also indicated above, the thickness of the plates may be varied depending upon the desired flexibility. Alternatively, the flat plate 80, or a plurality of such plates, may be assembled on the body 32 (FIG. 1) and seated against the retaining flange 36. The base ring 44 is then press fitted over the exterior of the body 32. The rim 45 of the base ring presses the area surrounding the opening 82 downwardly to thereby form the depressed center portion having the configuration shown in FIG. 7. Thus, it will be understood by those skilled in the art that the depressed center section of the plates may be either pre-formed before assembly or may be formed during the assembly process without departing from the spirit or scope of the present invention as defined by the claims.

FIG. 8 illustrates an alternative embodiment of the support pad constructed in accordance with the principles of the present invention. The support pad of FIG. 8 may be utilized when it is desired to change the flexibility of the support pad. Such changeability is provided by providing the body 90 with external threads 92. A collar 94 having internal threads is then threaded upon the body 92 and is positioned against the base ring 96 to hold the plates 98 and 100 against the plate retaining flange 102. As will be readily understood by those skilled in the art, when the operator utilizing the support pad as shown in FIG. 8 wishes to change the flexibility thereof either to make it more or less flexible, the collar 94 may be removed, the base ring 96 may then be removed and an additional plate added or one of the plates 98 or 100 removed depending upon whether less or more flexibility is desired for a particular application.

Through the utilization of the molybdenum disulfide filled nylon (or other plastic material) plates, the resulting structure is lighter in weight than the support pads of the prior art. In addition to the variable flexibility thereof, the support pad as illustrated in the present invention may be rotated at a much higher rate of speed than that of the prior art molded rubber pads currently being used. If the prior art molded rubber pads are rotated at the same speed as the support pad of the present invention, they would immediately deteriorate and effectively explode throwing particles thereof into the surrounding area. As is illustrated and has been described in detail above, the fastener surface holds the abrasive disc from the abrasive surface thereof in such a manner that the retaining flange on the fastener is below the operating surface of the abrasive disc thus providing a larger useful area and also precluding contact of the work piece by the fastener. As above illustrated, the abrasive disc is held in place and is gripped both by the upset portion of the fastener against the disc retaining flange and in addition when the abrasive finishing article is affixed to the support pad the disc retaining flange captures the disc and presses it against the depressed center area of the body of the support pad.

Referring now more particularly to FIGS. 9 through 12, there is illustrated an alternative structure of an abrasive finishing article constructed in accordance with the principles of the present invention. As is therein shown the fastener for the abrasive finishing article includes a threaded shaft 110 which has a radially outwardly extending flange 112 at one end thereof. A retaining member 114 in the form of a washer resiliently deformable is press fitted over the threads 116 on the shaft 110, abuts a surface 118 of an abrasive finishing article 120 such as a non-woven fibrous abrasive member. The washer 114 has an opening 122 centrally disposed therethrough which has a diameter d₂. The threaded shaft 110 has an outer diameter of the threads d₁. The diameter d₂ is slightly less than the diameter d₁ so that the washer 114 cannot be positioned over the threads 116 on the threaded shaft 110. The washer 114 is made of a resiliently deformable material such as plastic and preferably a polyamide plastic material. Such a material is flexible enough that if appropriate force is applied to the washer member 114 it may be press fitted over the threads 116 and when it abuts the surface 118 of the finishing article 120 will be secured permanently to the threaded shaft 110. When so press fitted the area around the opening 112 of the washer 114 will be deformed as illustrated at 124 and will effectively lock the washer 114 to the threaded shaft 110.

It should be understood that when the washer 114 is press fitted into place as shown in FIG. 12 sufficient force is applied so that the flange 112 is pulled inwardly away from the working surface 126 of the abrasive article 120, so that the flange is disposed entirely below the working surface 126. The force that is applied is sufficient to capture the disc 120 between the flange 112 and the washer 114, so that it is non-rotably secured to the fastener. It should also be noted that the end 128 of the threaded shaft 110 extends upwardly away from the surface 118 of the finishing of the disc 120. The threaded end 128 of the threaded shaft is adapted to be received within a threaded opening 130, which is formed within the body 132 of the support member 134 (FIG. 13). Support member 134 includes a radially outwardly extending flange 136 at the bottom end thereof. The opening 130 adjacent the flange 136 defines a cup shaped area 138 which is adapted to receive the area immediately surrounding the fastener as it is secured to the disc as is illustrated in FIG. 12. That is the cup shaped area 138 will allow the fastener to effectively pull the area immediately surrounding the threaded shaft 110 and the retainer 114 into the cup shaped area to more clearly and positively remove the flange 112 on the fastener from the working surface 126 of the abrasive finishing article 120.

By reference now to FIG. 14, it should be noted with the structure as illustrated in FIGS. 9 through 12 the resiliently deformable washer member provides a larger diameter to generate a greater holding power for the abrasive finishing article secured thereto as opposed to the structures described herein above. The resiliently deformable material of the retaining member allows the retaining member to be press fitted as opposed to being threaded onto the threaded shaft of the fastener. However, it is rigid enough to remain on the threads and to provide a force to securely and permanently hold the abrasive finishing article to the fastener by compressing the center of the disc between the flange and the washer. Because of its resilience the inner diameter of the washer will try to return to its non deformed state and will fit into the threads 140 as shown at 142 to prevent the washer from being removed from the fastener. It should be understood that through utilization of the structure as illustrated there is no adhesive of any type used to secure the abrasive finishing article to the fastener. The supporting member as illustrated in FIG. 13 provides extra flexibility for the abrasive finishing disc which is secured to the fastener as above described because it does not include the plates as above described.

There has thus been disclosed an abrasive finishing disc wherein a circular disc of abrasive finishing material is permanently secured by a fastening member which includes a press fitted resiliently deformable retaining member press fitted over a threaded shaft extending from a flange and protruding through a central opening in an abrasive disc, to rigidly and permanently clamp the abrasive disc to the fastener member without the necessity of utilizing adhesives and with sufficient force to cause the flange on the fastener to be disposed entirely below the working surface of the abrasive disc. 

1. An abrasive finishing disc for use with a support member having a threaded centrally disposed opening therethrough, said disc comprising: (a) a circular disc having first and second surfaces with abrasive finishing material on at least said first surface thereof and defining a centrally disposed opening therethrough; and (b) a fastener member including a threaded shaft having a diameter d₁ and having a flange extending radially outwardly from one end thereof, said threaded shaft extending through said centrally disposed opening in said circular disc with said flange engaging said first surface of said disc and said shaft extending beyond said second surface of said disc; and (c) a resiliently deformable retainer member press fitted over said threaded shaft, gripping said threads on said shaft and engaging said second surface with sufficient force to permanently secure said disc between said flange and said retainer member and to cause said flange to be entirely disposed below said first surface said disc.
 2. An abrasive finishing disc as defined in claim 1 wherein said resiliently deformable retainer member is a washer having an inner diameter d₂.
 3. An abrasive finishing disc as defined in claim 2 wherein said washer is constructed of a plastic material and diameter d₂ is less than diameter d₁.
 4. An abrasive finishing disc as defined in claim 3 wherein said washer is a polyamide material.
 5. An abrasive finishing disc as defined in claim 3 wherein said abrasive disc is constructed of a non-woven fibrous material.
 6. The combination of an abrasive disc support member and a disposable abrasive finishing disc comprising: (1) a support member including: (a) a cylindrical body having an outwardly extending flange engaging said disc, said body defining a centrally disposed threaded opening therethrough; and (b) said opening adjacent said flange defining a cup shaped recess for receiving a central portion of said abrasive disc; and (2) an abrasive disc comprising: (a) a circular disc having first and second surfaces with abrasive finishing material on at least said first surface thereof and defining a centrally disposed opening therethrough; and (b) a fastener member including a threaded shaft having a flange extending radially outwardly from one end thereof, said threaded shaft extending through said centrally disposed opening in said circular disc with said flange engaging said first surface of said disc and said shaft extending beyond said second surface of said disc; and (c) a resiliently deformable retainer member press fitted over said threaded shaft, gripping said threads on said shaft and engaging said second surface with sufficient force to permanently secure said disc between said flange and said retainer member and to cause said flange to be entirely disposed below said first surface of said disc; and (d) said threaded shaft being threadably received within said threaded opening in said cylindrical body.
 7. The combination as defined in claim 6 wherein said resiliently deformable retainer member is a washer.
 8. The combination as defined in claim 7 wherein said washer is constructed of a plastic material.
 9. The combination as defined in claim 8 wherein said washer is a polyamide material.
 10. The combination as defined in claim 8 wherein said abrasive disc is constructed of a non-woven fibrous material. 